1. Field of the Invention
The present invention relates to an image correction process for print-outputting, by a printer, digital image data obtained in a photographing operation by a digital still camera or the like.
2. Related Background Art
In recent years, with the spread of a digital still camera, digitization of photographed images comes into popular use. Especially, an opportunity of treating photographic images as digital image data on a personal computer increases. Furthermore, processing and editing can be easily performed to the digital image data being the photographic images by using various application software on the personal computer.
On the other hand, the technology in a full-color hardware copy is also rapidly progressed. Especially, in the print technology according to an ink jet system, image quality in a print-output result obtained by that system becomes the same as that in a print-output result obtained by a silver salt photographic method owing to improvement on technology of reducing granularity due to ink dots. Moreover, since the print technology according to the ink jet system is comparatively easy, this system has been widely spread.
According to such a technical background as above, it is required that the digital image data obtained by a photographing operation performed by the digital still camera can be easily print-output. With respect to an image correction process to be performed when image data is print-output, by using application software on the personal computer instead of performing a manual image correction process of using complicated functions, necessity of an automatic image correction process of always obtaining excellent images, to which the image correction process was performed, increases.
Therefore, in order to obtain an excellent print-output result, as a method of performing an image process such as the image correction process to image data and then print-outputting the processed data, there proposed various methods such as, for example, a method of analyzing a scene of a photographed image and automatically performing image correction on the basis of the analyzed result, and the like.
For example, there proposed a method related to so-called “density correction” being image correction of preventing an over-bright state (intensive pale color) or an over-dark state (intensive deep color) of a printed image when a photographed image is print-output. Also, there proposed a method related to so-called “image correction” of correcting an unpreferable image due to color fogging, defective exposure (defective lightness or defective contrast), defective saturation or the like on the photographed image and an image of defective color balance due to the color fogging or the like.
In either the image processing methods of “density correction” and “image correction”, as the structure for the purpose of automatic image correction, such the structure characterized in that a histogram of accumulating the number of pixels of a target brightness value to each brightness value of a brightness signal in an image (original image) to be processed is used to analyze the original image, which is corrected on the basis of the analyzed result, is employed.
As functions of the digital still camera, not only a function of recording image data obtained by a photographing operation in a storage medium such as a memory card or the like as digital image data but also a function of recording additional information of indicating a photographing condition at a time of photographing in the storage medium together with the digital image data can be realized.
Incidentally, in the above conventional image processing method, in case of analyzing a scene of a target image by analyzing an image to be processed (target image) obtained by a photographing operation performed by the digital still camera and performing the automatic image correction of the target image based on the analyzed result, such the automatic image correction of printing an image (standardized image) theoretically considered as the optimum one for all the target images is to be performed basically.
However, in case of performing the above automatic image correction, correction against the intention of a user at a time of obtaining a target image (time of performing a photographic operation) is sometimes performed.
For example, for an image obtained by performing a photographing operation under an exposure condition intended by the user to increase or decrease lightness of the image, if the image is light, it is corrected to slightly decrease the lightness, and if the image is dark, it is corrected to slightly increase the lightness. That is, even if the target image is any kind of image, the image is corrected as one of standard lightness and is output.
Furthermore, for an image to which a specific effect has been aimed by intentionally varying white balance of the digital still camera by the user, image correction of obtaining the optimum color balance is performed similar to a case for an image which was obtained by an ordinary photographing operation.
On the other hand, although the digital still camera has a function of a photographing mode which obtains the optimum photographing condition for a scene to be photographed, a method of determining an image correction condition based on the photographing mode is considered. If information of a photographed scene is previously recognized, that is, if it is the photographed scene of scenery, person or the like is previously recognized, it is considered that correction of achieving more precise and preferable images can be realized.
However, actually, since it is impossible to surely judge that the photographed scene corresponds to what kind of scene from the analyzed result of the target image which was obtained by photographing, only such a countermeasure has been found in a prior art, wherein the corrected effect according to the automatic image correction is weakened so that the harmful effect for an image does not occur.
With the advance of functions of the digital still camera in recent years, for example, there finds such a camera in which a specific effective function of increasing saturation or variably changing contrast or lightness for an image obtained by a photographing operation is provided. However, if an image correction process is performed to an image, to which the specific effective function is used, there sometimes occurred a case of deteriorating quality of the processed image due to a fact that a specific effect by the specific effective function is lost or correction by the specific effective function becomes intensive owing to double corrections.